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[PATCH] Kdump documentation update

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o Kdump documentation update.
	- Update details for using relocatable kernel.
	- Start using kexec-tools-testing release as it is latest and old
	  kexec-tools can't load relocatable bzImage file.
	- Also add kdump on ia64 specific details.

Signed-off-by: Vivek Goyal <vgoyal@in.ibm.com>
Cc: Horms <horms@verge.net.au>
Cc: Mohan Kumar M <mohan@in.ibm.com>
Signed-off-by: Andrew Morton <akpm@osdl.org>
Signed-off-by: Linus Torvalds <torvalds@osdl.org>
This commit is contained in:
Vivek Goyal 2007-01-10 23:15:35 -08:00 committed by Linus Torvalds
parent b282b6f8a8
commit 9c61a446a1
1 changed files with 155 additions and 75 deletions
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230
Documentation/kdump/kdump.txt
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@ -17,7 +17,7 @@ You can use common Linux commands, such as cp and scp, to copy the
memory image to a dump file on the local disk, or across the network to memory image to a dump file on the local disk, or across the network to
a remote system. a remote system.
Kdump and kexec are currently supported on the x86, x86_64, and ppc64 Kdump and kexec are currently supported on the x86, x86_64, ppc64 and IA64
architectures. architectures.
When the system kernel boots, it reserves a small section of memory for When the system kernel boots, it reserves a small section of memory for
@ -54,59 +54,64 @@ memory," in two ways:
Setup and Installation Setup and Installation
====================== ======================
Install kexec-tools and the Kdump patch Install kexec-tools
--------------------------------------- -------------------
1) Login as the root user. 1) Login as the root user.
2) Download the kexec-tools user-space package from the following URL: 2) Download the kexec-tools user-space package from the following URL:
http://www.xmission.com/~ebiederm/files/kexec/kexec-tools-1.101.tar.gz http://www.kernel.org/pub/linux/kernel/people/horms/kexec-tools/kexec-tools-testing-20061214.tar.gz
Note: Latest kexec-tools-testing git tree is available at
git://git.kernel.org/pub/scm/linux/kernel/git/horms/kexec-tools-testing.git
or
http://www.kernel.org/git/?p=linux/kernel/git/horms/kexec-tools-testing.git;a=summary
3) Unpack the tarball with the tar command, as follows: 3) Unpack the tarball with the tar command, as follows:
tar xvpzf kexec-tools-1.101.tar.gz tar xvpzf kexec-tools-testing-20061214.tar.gz
4) Download the latest consolidated Kdump patch from the following URL: 4) Change to the kexec-tools-1.101 directory, as follows:
http://lse.sourceforge.net/kdump/ cd kexec-tools-testing-20061214
(This location is being used until all the user-space Kdump patches 5) Configure the package, as follows:
are integrated with the kexec-tools package.)
5) Change to the kexec-tools-1.101 directory, as follows:
cd kexec-tools-1.101
6) Apply the consolidated patch to the kexec-tools-1.101 source tree
with the patch command, as follows. (Modify the path to the downloaded
patch as necessary.)
patch -p1 < /path-to-kdump-patch/kexec-tools-1.101-kdump.patch
7) Configure the package, as follows:
./configure ./configure
8) Compile the package, as follows: 6) Compile the package, as follows:
make make
9) Install the package, as follows: 7) Install the package, as follows:
make install make install
Download and build the system and dump-capture kernels Build the system and dump-capture kernels
------------------------------------------------------ -----------------------------------------
There are two possible methods of using Kdump.
Download the mainline (vanilla) kernel source code (2.6.13-rc1 or newer) 1) Build a separate custom dump-capture kernel for capturing the
from http://www.kernel.org. Two kernels must be built: a system kernel kernel core dump.
and a dump-capture kernel. Use the following steps to configure these
kernels with the necessary kexec and Kdump features:
System kernel 2) Or use the system kernel binary itself as dump-capture kernel and there is
------------- no need to build a separate dump-capture kernel. This is possible
only with the architecutres which support a relocatable kernel. As
of today i386 and ia64 architectures support relocatable kernel.
Building a relocatable kernel is advantageous from the point of view that
one does not have to build a second kernel for capturing the dump. But
at the same time one might want to build a custom dump capture kernel
suitable to his needs.
Following are the configuration setting required for system and
dump-capture kernels for enabling kdump support.
System kernel config options
----------------------------
1) Enable "kexec system call" in "Processor type and features." 1) Enable "kexec system call" in "Processor type and features."
@ -132,89 +137,161 @@ System kernel
analysis tools require a vmlinux with debug symbols in order to read analysis tools require a vmlinux with debug symbols in order to read
and analyze a dump file. and analyze a dump file.
4) Make and install the kernel and its modules. Update the boot loader Dump-capture kernel config options (Arch Independent)
(such as grub, yaboot, or lilo) configuration files as necessary. -----------------------------------------------------
5) Boot the system kernel with the boot parameter "crashkernel=Y@X", 1) Enable "kernel crash dumps" support under "Processor type and
where Y specifies how much memory to reserve for the dump-capture kernel features":
and X specifies the beginning of this reserved memory. For example,
"crashkernel=64M@16M" tells the system kernel to reserve 64 MB of memory
starting at physical address 0x01000000 for the dump-capture kernel.
On x86 and x86_64, use "crashkernel=64M@16M". CONFIG_CRASH_DUMP=y
On ppc64, use "crashkernel=128M@32M". 2) Enable "/proc/vmcore support" under "Filesystems" -> "Pseudo filesystems".
CONFIG_PROC_VMCORE=y
(CONFIG_PROC_VMCORE is set by default when CONFIG_CRASH_DUMP is selected.)
The dump-capture kernel Dump-capture kernel config options (Arch Dependent, i386)
----------------------- --------------------------------------------------------
1) On x86, enable high memory support under "Processor type and
1) Under "General setup," append "-kdump" to the current string in
"Local version."
2) On x86, enable high memory support under "Processor type and
features": features":
CONFIG_HIGHMEM64G=y CONFIG_HIGHMEM64G=y
or or
CONFIG_HIGHMEM4G CONFIG_HIGHMEM4G
3) On x86 and x86_64, disable symmetric multi-processing support 2) On x86 and x86_64, disable symmetric multi-processing support
under "Processor type and features": under "Processor type and features":
CONFIG_SMP=n CONFIG_SMP=n
(If CONFIG_SMP=y, then specify maxcpus=1 on the kernel command line (If CONFIG_SMP=y, then specify maxcpus=1 on the kernel command line
when loading the dump-capture kernel, see section "Load the Dump-capture when loading the dump-capture kernel, see section "Load the Dump-capture
Kernel".) Kernel".)
4) On ppc64, disable NUMA support and enable EMBEDDED support: 3) If one wants to build and use a relocatable kernel,
Enable "Build a relocatable kernel" support under "Processor type and
features"
CONFIG_NUMA=n CONFIG_RELOCATABLE=y
CONFIG_EMBEDDED=y
CONFIG_EEH=N for the dump-capture kernel
5) Enable "kernel crash dumps" support under "Processor type and 4) Use a suitable value for "Physical address where the kernel is
features": loaded" (under "Processor type and features"). This only appears when
"kernel crash dumps" is enabled. A suitable value depends upon
whether kernel is relocatable or not.
CONFIG_CRASH_DUMP=y If you are using a relocatable kernel use CONFIG_PHYSICAL_START=0x100000
This will compile the kernel for physical address 1MB, but given the fact
kernel is relocatable, it can be run from any physical address hence
kexec boot loader will load it in memory region reserved for dump-capture
kernel.
6) Use a suitable value for "Physical address where the kernel is Otherwise it should be the start of memory region reserved for
second kernel using boot parameter "crashkernel=Y@X". Here X is
start of memory region reserved for dump-capture kernel.
Generally X is 16MB (0x1000000). So you can set
CONFIG_PHYSICAL_START=0x1000000
5) Make and install the kernel and its modules. DO NOT add this kernel
to the boot loader configuration files.
Dump-capture kernel config options (Arch Dependent, x86_64)
----------------------------------------------------------
1) On x86 and x86_64, disable symmetric multi-processing support
under "Processor type and features":
CONFIG_SMP=n
(If CONFIG_SMP=y, then specify maxcpus=1 on the kernel command line
when loading the dump-capture kernel, see section "Load the Dump-capture
Kernel".)
2) Use a suitable value for "Physical address where the kernel is
loaded" (under "Processor type and features"). This only appears when loaded" (under "Processor type and features"). This only appears when
"kernel crash dumps" is enabled. By default this value is 0x1000000 "kernel crash dumps" is enabled. By default this value is 0x1000000
(16MB). It should be the same as X in the "crashkernel=Y@X" boot (16MB). It should be the same as X in the "crashkernel=Y@X" boot
parameter discussed above. parameter.
On x86 and x86_64, use "CONFIG_PHYSICAL_START=0x1000000". For x86_64, normally "CONFIG_PHYSICAL_START=0x1000000".
On ppc64 the value is automatically set at 32MB when 3) Make and install the kernel and its modules. DO NOT add this kernel
CONFIG_CRASH_DUMP is set.
6) Optionally enable "/proc/vmcore support" under "Filesystems" ->
"Pseudo filesystems".
CONFIG_PROC_VMCORE=y
(CONFIG_PROC_VMCORE is set by default when CONFIG_CRASH_DUMP is selected.)
7) Make and install the kernel and its modules. DO NOT add this kernel
to the boot loader configuration files. to the boot loader configuration files.
Dump-capture kernel config options (Arch Dependent, ppc64)
----------------------------------------------------------
- Make and install the kernel and its modules. DO NOT add this kernel
to the boot loader configuration files.
Dump-capture kernel config options (Arch Dependent, ia64)
----------------------------------------------------------
(To be filled)
Boot into System Kernel
=======================
1) Make and install the kernel and its modules. Update the boot loader
(such as grub, yaboot, or lilo) configuration files as necessary.
2) Boot the system kernel with the boot parameter "crashkernel=Y@X",
where Y specifies how much memory to reserve for the dump-capture kernel
and X specifies the beginning of this reserved memory. For example,
"crashkernel=64M@16M" tells the system kernel to reserve 64 MB of memory
starting at physical address 0x01000000 (16MB) for the dump-capture kernel.
On x86 and x86_64, use "crashkernel=64M@16M".
On ppc64, use "crashkernel=128M@32M".
Load the Dump-capture Kernel Load the Dump-capture Kernel
============================ ============================
After booting to the system kernel, load the dump-capture kernel using After booting to the system kernel, dump-capture kernel needs to be
the following command: loaded.
kexec -p <dump-capture-kernel> \ Based on the architecture and type of image (relocatable or not), one
can choose to load the uncompressed vmlinux or compressed bzImage/vmlinuz
of dump-capture kernel. Following is the summary.
For i386:
- Use vmlinux if kernel is not relocatable.
- Use bzImage/vmlinuz if kernel is relocatable.
For x86_64:
- Use vmlinux
For ppc64:
- Use vmlinux
For ia64:
(To be filled)
If you are using a uncompressed vmlinux image then use following command
to load dump-capture kernel.
kexec -p <dump-capture-kernel-vmlinux-image> \
--initrd=<initrd-for-dump-capture-kernel> --args-linux \ --initrd=<initrd-for-dump-capture-kernel> --args-linux \
--append="root=<root-dev> init 1 irqpoll" --append="root=<root-dev> <arch-specific-options>"
If you are using a compressed bzImage/vmlinuz, then use following command
to load dump-capture kernel.
kexec -p <dump-capture-kernel-bzImage> \
--initrd=<initrd-for-dump-capture-kernel> \
--append="root=<root-dev> <arch-specific-options>"
Following are the arch specific command line options to be used while
loading dump-capture kernel.
For i386 and x86_64:
"init 1 irqpoll maxcpus=1"
For ppc64:
"init 1 maxcpus=1 noirqdistrib"
For IA64
(To be filled)
Notes on loading the dump-capture kernel: Notes on loading the dump-capture kernel:
* <dump-capture-kernel> must be a vmlinux image (that is, an
uncompressed ELF image). bzImage does not work at this time.
* By default, the ELF headers are stored in ELF64 format to support * By default, the ELF headers are stored in ELF64 format to support
systems with more than 4GB memory. The --elf32-core-headers option can systems with more than 4GB memory. The --elf32-core-headers option can
be used to force the generation of ELF32 headers. This is necessary be used to force the generation of ELF32 headers. This is necessary
@ -231,6 +308,9 @@ Notes on loading the dump-capture kernel:
* "init 1" boots the dump-capture kernel into single-user mode without * "init 1" boots the dump-capture kernel into single-user mode without
networking. If you want networking, use "init 3." networking. If you want networking, use "init 3."
* We generally don' have to bring up a SMP kernel just to capture the
dump. Hence generally it is useful either to build a UP dump-capture
kernel or specify maxcpus=1 option while loading dump-capture kernel.
Kernel Panic Kernel Panic
============ ============